Low Points

Low Point grading objects, along with Drain Lines, are drain elements that control the slope direction of surface triangles. The Low Point directs triangles toward the low point location.

Using the Wireframe theme and Hydrology Direction Vectors in the Visualization Toolbar, you can better see how Grading Optimization will attempt to solve the surface grading for drainage.

You can also specify a diamond shape pattern for the slope (instead of this default circular pattern) in the Low Point Properties Panel.

There can be multiple drainage elements in a model and each triangle will point toward the closest drainage element based on the centroid of the triangle.